Immediate release pharmaceutical granule compositions and a continuous process for making them

ABSTRACT

A pharmaceutical or veterinary granule composition in the form of a mixture consisting essentially of: (i) at least one drug classifiable as Class II or Class IV of the Biopharmaceutical Classification System, wherein said drug (i) constitutes from 0.5% to 20% by weight of the composition, and excipients, said pharmaceutical or veterinary granule composition providing a drug release of at least 70% within 10 minutes in water, (ii) a first excipient being a maltodextrin representing from 40% by weight to 80% by weight of said composition, (iii) a wetting amount of a second excipient being a polyethylene glycol having a weight number molecular weight between 300 and 5,000, said second excipient comprising a solid fraction and a liquid fraction, and representing from 15% to 40% by weight of said composition, and optionally one or more pharmaceutically acceptable fillers selected from the group consisting of hydrocolloids, glidants, lubricants, surfactants and diluents, wherein the weight ratio of said first excipient (ii) to said second excipient (iii) is in a range from 1:1 to 5:1.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/933,674, filed on Sep. 3, 2004, which is a continuation-in-part ofInternational Application No. PCT/BE03/00040, filed on Mar. 5, 2003,which was published in English under PCT Article 21(2), and which claimsbenefit of British Patent Application No. 0205253.8, filed on Mar. 6,2002, the disclosures of which are hereby incorporated by reference intheir entirety.

FIELD OF THE INVENTION

The present invention is in the field of drug delivery systems andimmediate release technology. Particularly, the invention is in thefield of immediate or fast release pharmaceutical solid, preferablygranule, compositions. More specifically, the invention relates to suchcompositions with low to moderate and even high drug loading forimmediate or fast release of drugs which have low or very low solubilityin water. The invention also relates to various solid pharmaceuticaldosage forms such as sachets, gelules and tablets including suchimmediate or fast release pharmaceutical granule compositions. Stillmore specifically, the invention relates to immediate or fast releasewater-soluble granule veterinary compositions which can readily beadministered to animals together with drinking water. Finally theinvention relates to a continuous process for manufacturing saidimmediate or fast release pharmaceutical or veterinary granulecompositions.

BACKGROUND OF THE INVENTION

Some general considerations relating to drug formulation are providedherein in order to understand the constraints applicable to theformulation of drugs which have low solubility in water and at the sametime the kind of pharmaceutical solid formulations to which the presentinvention relates.

Tablets and capsules are generally unsuitable for administering highdoses of biologically active ingredients since individual large dosageforms are difficult to swallow or necessitate the administration ofseveral tablets or capsules at a time, leading to impaired patientcompliance.

Hard gelatin capsules are known as a conventional pharmaceutical dosageform. Their sizes have been standard since the start of industrialmanufacture of drug compositions, ranging from 5 (corresponding to avolume of 0.13 ml) up to 000 (corresponding to a volume of 1.36 ml).Thus, when a large amount of ingredient is required for each dosageunit, depending on the bulk density of the formulation, it may benecessary to use large size capsules which are too large to swallow or,even worse, a size 000 capsule may be too small to receive the saidamount. Pellets and granules have been filled into hard gelatin capsulesto be used as conventional or controlled release dosage forms, howeverthe latter are rather difficult to manufacture.

The concept of tabletting coated active ingredient particles istherefore of major interest. Attempts have been made to produce tabletscomprising microcapsules because of the advantages resulting from themicroencapsulated substance being protected from external influences andvice-versa, e.g. increased stability, reduced chances of irritations orundesirable reactions with other components in a mixture, ability tomask unpleasant tastes and smells, etc. However, compaction of coatedbeads or pellets for making tablets encounters many difficulties andproblems. As is well known in the pharmaceutical industry, beads orpellets are quite distinguishable from granules. Beads can be defined assmall, free-flowing spherical or sphere-like particulates manufacturedby pelletization, i.e. the agglomeration of fine powders or granules ofdrug substances and excipients using appropriate processing equipment.As opposed to the process of granulation, the production of beads bypelletization results in a larger average size and a narrower size-rangedistribution.

Another difficult problem is the formulation of drugs having low or verylow water-solubility into solid dosage forms for immediate release. Fewsolutions to this problem have been disclosed in the art. For instance,U.S. Patent Publication No. 2001/0048946 provides solid dosage forms ofsparingly water-soluble pharmaceutical agents, i.e. solid or crystallinedrugs having a water-solubility of 10 to 33 μg/ml at 25° C., such asglitazones. More particularly, this document discloses a pharmaceuticalcomposition in the form of a solid particulate dispersion of such apharmaceutical agent dispersed throughout a matrix of a water-solublepolymer such as polyvinylpyrrolidone, hydroxypropyl cellulose, orhydroxypropyl methylcellulose. In a preferred embodiment, theparticulate pharmaceutical agent is dispersed in the water-solublepolymer in a weight ratio of about 10% to about 90% active ingredient toabout 90% to about 10% polymer. Other conventional excipients such asglycerin, propylene glycol, Tween, stearic acid salts and the like canbe added.

U.S. Patent Publication No. 2001/0044409 discloses a process for thepreparation of a poorly water soluble drug in solid dispersioncomprising the steps of (a) blending the drug with a carrier, (b)dissolving a surfactant and a plasticizer/solubilizer in water, (c)spraying the surfactant-plasticizer/solubilizer solution onto thedrug/carrier mixture in a fluid bed granulator, (d) extruding theresulting granulation through a twin screw extruder with at least oneheating zone, and (e) milling the extrudate to a powdery mass of thesolid drug dispersion. Within the scope of this process, said carriermay be selected from the group consisting of polyvinylpyrrolidone, highmolecular weight polyethylene glycol, urea, citric acid, vinyl acetatecopolymer, acrylic polymers, succinic acid, sugars and mixtures thereof;the said plasticizer/solubilizer may be selected from the groupconsisting of low molecular weight polyethylene glycol, propyleneglycol, glycerin, triacetin, triethyl citrate, sugar alcohols andmixtures thereof, and the said surfactant may be selected from the groupconsisting of Tween, Span, Pluronics, polyoxyethylene sorbitol esters,monodiglycerides, polyoxyethylene acid polyoxyethylene alcohol andmixtures thereof. This process suffers from the disadvantage ofproviding a heating zone in the twin screw extruder and consequently aneed for controlling and monitoring the temperature profile of theextruder for efficient quality control.

However, none of the above processes appear to be successful informulating solid dosage forms of drugs having very lowwater-solubility, i.e. a solubility lower than 10 μg/ml, preferablylower than 5 μg/ml. This problem is applicable to a large number ofdrugs, including those belonging to the family of diamino-pyrimidines,such as stated in U.S. Pat. No. 6,211,185.

U.S. Pat. No. 3,639,637 discloses oestrogen compositions for thepreparation of stable aqueous suspensions that can be sprayed ontoanimal feed, comprising (by weight) 70-95% of water-dispersiblegel-forming microcrystalline cellulose and 5-30% of finely-divideddiethylstilbestrol (a compound which is virtually insoluble in water)and optionally further up to one third of the weight of the compositionof a hydrocolloid selected from the group consisting of sodiumcarboxy-methylcellulose, methylcellulose and hydroxyethylcellulose. Thetwo latter cellulose compounds are known, namely from EP-A-403,383, tocontribute to an extended linear drug release rate.

EP-A-352,190 discloses a solid pharmaceutical unit with a delayeddissolution of the active ingredient, i.e. allowing retention of theactive ingredient and avoiding its complete and immediate availabilityby a simple contact with an aqueous liquid medium. It further disclosesin example 9 paracetamol micro-granules obtained from a mixture of 182 gparacetamol (a drug belonging to class I of the BiopharmaceuticalClassification System and having a water-solubility of 14 mg/ml), 728 gmicrocrystalline cellulose (AVICEL PH 101) and 90 g sodiumcarboxymethylcellulose. EP-A-352,190 however does not teach using acyclodextrin compound as a drug dissolution enhancer.

U.S. Pat. No. 5,362,860 discloses (see table VI, example C) acomposition with improved storage stability comprising (by weight) 0.05%of a pyridine based oxime (a drug undergoing hydrolysis into an aldehydein an acidic environment), 70% cyclodextrin, 3% crosscarmellose (acrosslinked polymer) and 20.95% microcrystalline cellulose.

WO-A-99/12,524 solves the problem of drug formulations with both arelatively fast or quick onset of the therapeutic effect and themaintenance of a therapeutically active plasma concentration for arelatively long period of time, by providing an oral modified releasemultiple-units composition wherein the unit dosage form comprises atleast (i) a first fraction being able to release at least 50% of thedrug within the first 20 minutes of a certain dissolution method, and(ii) a second fraction for delayed and extended release of the drug. Themultiple-units of the first fraction may be granulates or, provided thata surfactant is added to the formulation, coated or uncoated pellets.Formulation of the first fraction depends on the specific drug buttypically includes wet-granulation, and an antacid-like or otheralkaline substance was found to have a pronounced increasing effect onthe release rate.

U.S. Pat. No. 5,646,131 discloses (example 4) rapidly dissolvingcapsules containing a granulate formulation of a water-insoluble orsparingly soluble drug, such as terfenadine (less than 0.01 mg/mlwater-solubility), surfactants (Tween 80 and sodium lauryl sulfate),cyclodextrin, Avicel PH 101 (microcrystalline cellulose) and adisintegrant/swelling agent (Primojel®, i.e. sodium carboxy-methylstarch) in a weight ratio of 10:72 to Avicel. These capsules providebetter drug absorption, due to the presence of cyclodextrin, asevidenced by the figure showing a 90% drug release within 45 minutes.

Elbers et al. in Drug Development and Industrial Pharmacy (1992)18(5):501-517 discloses theophylline pellets with a drug loading from 10to 50% obtained by extrusion-spheronization with AVICEL 581 (a blend ofmicrocrystalline cellulose and sodium carboxymethylcellulose).Theophylline is a drug with a water-solubility of 8 mg/ml (according toMerck Index, 12^(th) edition 1996) and high permeability (according toFDA Guidance to Industry, 2000), thus belonging to class I of theBiopharmaceutical Classification System.

U.S. Pat. No. 4,235,892 discloses a series of1-aryl-2-acylamido-3-fluoro-1-propanol antibacterial agents includingD-(threo)-1-p-methylsulfonylphenyl-2-dichloroacetamido-3-fluoro-1-propanol, an antibacterial agentknown as florfenicol and useful for veterinary purposes. Florfenicol haslow solubility in water (about 1.3 mg/ml), as well as in manypharmaceutically acceptable organic solvents such as 1,2-propanediol,glycerin, and benzyl alcohol. For oral administration, these1-aryl-2-acylamido-3-fluoro-1-propanol may be compounded in the form oftablets, or may even be admixed with animal feed. U.S. Pat. No.4,235,892 therefore discloses making tablets by compressing granules ofa composition comprising the said 1-aryl-2-acylamido-3-fluoro-1-propanol(in a drug loading range from 8.3% to 41.7% by weight), lactose,microcrystalline cellulose, starch and magnesium stearate.

The Biopharmaceutical Classification System (hereinafter referred asBCS) according to G. Amidon et al. in Pharm. Res. (1995) 12:413-420provides for two classes of poorly soluble drugs, i.e. Class II andClass IV, and a class of highly soluble drugs, i.e. Class I. Accordingto M. Martinez et al., Applying the Biopharmaceutical ClassificationSystem to Veterinary Pharmaceutical Products (Part I: Biopharmaceuticsand Formulation Consideration) in Advanced Drug Delivery Reviews (2002)54:805-824, a drug substance should be classified as highly soluble whenthe highest dose strength is soluble in at most 250 ml of aqueous mediaover the pH range 1-7.5. In view of its water solubility (1.3 mg/ml) andof a maximal dose of 20 mg/kg for pigs, it is easy to calculate that thehighest dose strength of florfenicol administered to pigs is soluble inan amount of water which is well above the limit value for thedefinition of a class 1 BCS highly soluble drug. Furthermore it is knownfrom J. Voorspoels et al. in The Veterinary Record (October 1999) thatflorfenicol has a good oral bioavailability, so that it can beclassified as a Class II compound as it is not a highly soluble drug andit shows no absorption problems.

U.S. Pat. No. 6,368,634 discloses a solid preparation suitable for asubstantially immediate release of an active agent having a low or verylow solubility, for example wherein more than 80% of the active agent isreleased within 2 hours, preferably within 1 hour or less from theadministration. This solid preparation is obtained by pelletisation,i.e. an agglomeration process whereby fine powders or granules areshaped into fine, free-flowing units (pellets) with a particle sizeabove 250 μm. The pellets of this solid preparation comprise one or morecarriers (which may be polymers, or inorganic carriers such as talc,montmorillonite, bentonite, clay or calcium phosphate) and an activeingredient dissolved in a liquid phase (liquid as such or to beliquified for example by means of shear or temperature) which may be anoil or fat, a tensio-active agent or a polar co-solvent (such aspolyethylene glycol, glycerol or propylene glycol). In U.S. Pat. No.6,368,634 the active ingredient is dissolved in a liquid solubilizer(the weight ratio solubilizer/active agent being greater than 4) whichis fixed on solid carrier particles preferably with a particle sizebelow 500 μm such as microcrystalline cellulose, the resulting mixturebeing then transformed into pellets using a suitable batch techniquesuch as extrusion/spheronisation, fluid-bed technology, rotarygranulation. As a result the active ingredient is already in solutioninside the dosage form (i.e. pellets) and hence is very quickly releasedfrom the dosage form upon contact with aqueous media. Thereforeaccording to U.S. Pat. No. 6,368,634 it is essential to have a liquidphase in which the active ingredient can dissolve to obtain the reporteddissolution profiles.

FIGS. 6 and 7 of U.S. Pat. No. 6,368,634 clearly illustrate that theactive ingredient is no longer in its crystalline form inside the dosageform, but has gone into solution in the solubilizer. No peaks ofcrystalline hydrochlorothiazide (at 2θ=19°) are present in the X-raydiffraction pattern of pellets containing 3.5% by weighthydrochlorothiazide (HCT) and 32% by weight polyethylene glycol with amolecular weight of 400, as shown in FIGS. 6B and 6C. The importance ofthe active agent being dissolved in the liquid solubilizer is clearlyshown in example 4 in combination with FIGS. 5 and 7 of U.S. Pat. No.6,368,634. FIG. 5 shows a higher dissolution rate after 6 months storageof pellets containing 3.5% by weight HCT and 21% by weight polyethyleneglycol hydrogenated castor oil. Immediately after preparation acrystalline peak of HCT was still visible (FIG. 7A), whereas it haddisappeared after 6 months storage (FIG. 7B), i.e. all HCT crystals haddissolved, this behaviour being also indicative of a need forcontrolling drug formulation stability during storage. An increaseddissolution rate was obtained after heat treatment of the pelletsimmediately after preparation, this again corresponding to the completedrug fraction going into solution as shown in FIG. 7C.

A limitation of the technology disclosed in U.S. Pat. No. 6,368,634 isthat it only allows to increase the dissolution rate of formulationscontaining a low content of active ingredient (i.e. drug loading) sincethe amount of liquid phase (solubilizer) that can be fixed onto thesolid carrier particles is limited to a weight ratiosolubilizer/particles from 1:5 to 1:2, and the active ingredient furtherneeds to dissolve into the solubilizer. This limitation is wellillustrated in U.S. Pat. No. 6,368,634 teaching drug loadings in a rangefrom about 1% by weight (examples 1 and 9) to about 6/% by weight(example 5). This limitation was confirmed by our experiments performedwhile preparing a pellet formulation based on the teachings of U.S. Pat.No. 6,368,634 but containing 20% by weight of a veterinary activeingredient. The release rate of this ingredient from the pellets was lowand this slow drug release from the pellets was also reflected in lowplasma levels of broiler chickens after administration of thisformulation via drinking water.

Furthermore, U.S. Pat. No. 6,368,634 describes the dosage form aspellets which are produced by a suitable batch technique such asfluid-bed technology, rotary granulation or, preferably,extrusion-spheronisation. The extrusion-spheronisation process is amulti-step process capable of making uniformly sized preferablyspherical particles (pellets). The following steps are required: (a) drymixing, (b) wet granulation (i.e. formation of a wet mass, e.g. in U.S.Pat. No. 6,368,634 through the addition of a liquid phase and water (inorder to get sufficient plasticity for extrusion), (c) extrusion (i.e.forming the wet mass into long rod-shaped particles), (d) spheronisation(breaking the rod-shaped particles into smaller pieces and rounding theindividual particles into spheres) and (e) drying (removal of wateradded during granulation). Another limitation of the technologydisclosed in U.S. Pat. No. 6,368,634 is thus that the stickiness of thewet mass formed in step (b) should not exceed a level where itsextrusion in step (c) would become impossible and/or would block theextruder. This proviso implies significant limitations on the liquidsolubilizer that may be used according to U.S. Pat. No. 6,368,634. Inparticular, the latter document does not teach or suggest the use ofmaltodextrins, and the skilled person knows that a mixture of water anda maltodextrin would have a stickiness much higher than permitted forextrusion. Another limitation of this technology is the need for anenergy-consuming drying step in the final stage of theextrusion-spheronisation process.

Therefore, there is still a need in the art for formulating poorlysoluble drugs classifiable as or belonging to Class II or Class IV ofthe Biopharmaceutical Classification System not only into formulationswith low drug contents (such as known from U.S. Pat. No. 6,368,634) butalso into formulations with moderate and even high drug contents. Thereis also a need in the art for making formulations of poorly solubledrugs classifiable as or belonging to Class II or Class IV of theBiopharma-ceutical Classification System by means of a continuousproduction method, not a batch-wise production method, in order todecrease their production cost. There is also a need in the art formaking formulations of poorly soluble drugs classifiable as or belongingto Class II or Class IV of the Biopharma-ceutical Classification Systemby an energy-saving production method which does not require a dryingstep, in order to decrease their production cost. There is also a needin the art for formulating poorly soluble drugs classifiable as orbelonging to Class II or Class IV of the BiopharmaceuticalClassification System as granules, not pellets. There is also a need inthe art for formulating poorly soluble drugs classifiable as orbelonging to Class II or Class IV of the Biopharma-ceuticalClassification System in the absence of a costly pharmaceutical gradematerial such as microcrystalline cellulose.

There is a specific need in the art to provide a solid formulation ofdrugs with a water-solubility like florfenicol or lower. Florfenicol isa drug for administration to warm-blooded animals, such as cattle withnaturally-occurring bovine respiratory disease, swine, sheep, goats andpoultry, which at present is mainly available in the form of injectablesolutions. Until now the skilled person has failed in the design of sucha solid formulation of florfenicol, which can further be admixed withanimal feed if necessary. There is therefore a need in the art for aflorfenicol formulation in the form of a water-soluble granulate foradministration to animals together with drinking water. Also there is aneed for a solid formulation for many low solubility drugs for human andveterinary therapies.

SUMMARY OF THE INVENTION

The present invention is based on the unexpected finding that drugsclassifiable as or belonging to Class II (poorly soluble, highlypermeable) or Class IV (poorly soluble, poorly permeable) of theBiopharmaceutical Classification System, including drugs having very lowwater-solubility, can be successfully formulated into immediate or fastrelease pharmaceutical solid dosage forms provided that:

-   (1) they are admixed in suitable proportions with a first    pharmaceutically acceptable excipient comprising a    dextrin-containing compound or, in a less preferred embodiment, a    blend of microcrystalline cellulose and a swellable polymer, or a    mixture of the said dextrin-containing compound and the said blend,    and with a second pharmaceutically acceptable excipient being a    non-aqueous wetting compound comprising at least a solid fraction,    and that-   (2) they are formulated into granule compositions, not pellet    compositions.    Preferably, these granule formulations are advantageously obtained    by a continuous manufacturing process involving a low temperature    extruding step in an extruding means. Based on the above teachings,    the invention also provides various pharmaceutical dosage forms such    as sachets and solid shaped articles such as tablets and hard    gelatin capsules including the said granule compositions. The    invention also provides water-soluble granule compositions of poorly    soluble drugs that may be administered to animals in admixture with    drinking water. The invention also relates to the treatment of    bacterial infections in human beings and in animals, such as    poultry, pigs, cattle (e.g. the treatment of bovine respiratory    disease) and fish, by the oral administration to the human being or    animal of an effective amount of the above-referred immediate or    fast release pharmaceutical granule compositions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents the release, as a function of time, ofhydrochlorothiazide from a granule composition according to oneembodiment of the invention.

FIG. 2 represents the release, as a function of time, of florfenicolfrom a granule composition according to one embodiment of the invention.

FIG. 3 shows a twin screw extruder useful for manufacturing granulecompositions according to one embodiment of the present invention.

FIG. 4 shows the release, as a function of time, of florfenicol from apellet composition according to the prior art.

FIG. 5 shows florfenicol plasma concentrations in chickens afteradministration of a bolus dose of a florfenicol granule compositionaccording to one embodiment of the invention, compared to intravenousadministration of the same dose.

FIG. 6 shows florfenicol plasma concentrations in pigs afteradministration of a bolus dose of a florfenicol granule compositionaccording to one embodiment of the invention, compared to intravenousadministration of the same dose.

FIG. 7 shows florfenicol plasma concentrations in chickens, as afunction of time, after continuous administration of a florfenicolgranule composition according to one embodiment of the invention,compared to a florfenicol pellet composition of the prior art.

DEFINITIONS

The terms “low drug content” and “low drug loading” as used herein,unless otherwise stated, are intended to mean a drug content, withrespect to the total solid formulation, in a range below about 7% byweight.

The terms “moderate drug content” and “moderate drug loading” as usedherein, unless otherwise stated, are intended to mean a drug content,with respect to the total solid formulation, in a range from about 7% byweight to about 20% by weight.

The terms “high drug content” and “high drug loading” as used herein,unless otherwise stated, are intended to mean a drug content, withrespect to the total solid formulation, in a range above about 20% byweight.

The term “solid shaped article” as used herein means any article beingin a hard solid state at temperatures not exceeding about 60° C. andhaving a definite geometrical shape, such as for instance ordinarytablets, effervescent tablets, pills, lozenges and other compresseddosage forms.

The term “immediate release” as used herein means a release of at leastabout 50% of a drug within 30 minutes in water, preferably a release ofat least about 70% of said drug within 10 minutes in water, and morepreferably a release of at least about 80% of said drug within 10minutes in water, under physiological temperature and pH conditions.

The term “fast release” as used herein means a release from about 40% toabout 50% of a drug within 30 minutes in water, under physiologicaltemperature and pH conditions.

DETAILED DESCRIPTION OF THE INVENTION

In a first embodiment, this invention relates to an immediate or fastrelease pharmaceutical solid composition comprising at least one drug(i) classifiable as Class II (poorly soluble, highly permeable) or ClassIV (poorly soluble, poorly permeable) of the BiopharmaceuticalClassification System, e.g. a drug having very low water-solubility suchas defined herein, wherein said drug is present in said solidcomposition in a low drug content, a moderate drug content or a highdrug content, i.e. said drug constitutes at least about 0.5% by weightbut no more than 50% by weight, for instance from 0.5% to about 20% byweight (low and moderate drug loadings), preferably from 1 to 15% byweight, or alternatively from 20% to 50% by weight (high drug loadings)of the solid composition, wherein said solid composition is in the formof granules comprising one or more pharmaceutically acceptableexcipients, wherein said one or more pharmaceutically acceptableexcipients comprise

(ii) a first excipient selected from the group consisting of:

-   -   blends of a microcrystalline cellulose and a swellable polymer        in respective amounts such that the weight ratio of the said        polymer to the microcrystalline cellulose in the blend is above        about 2:100 and up to about 30:100,    -   one or more dextrin-containing compounds selected from the group        consisting of maltodextrins, cyclodextrins and derivatives        thereof, and    -   mixtures of the said dextrin-containing compounds and the said        blends, and        (iii) a wetting amount of a second excipient being a non-aqueous        wetting compound or meltable compound and comprising a solid        fraction and optionally a liquid fraction.

In a second embodiment, this invention relates to a continuous processfor manufacturing the aforesaid immediate or fast release solidpharmaceutical composition. More particularly, this invention provides acontinuous process for manufacturing a pharmaceutical granulecomposition comprising at least one drug (i) classifiable as Class II orClass IV of the Biopharma-ceutical Classification System in an amount ofno more than about 50% by weight, for instance from 0.5% to about 20% byweight (low and moderate drug loadings), preferably from 1 to 15% byweight, or alternatively from 20% to 50% by weight (high drug loadings),of said pharmaceutical composition, a first excipient (ii) being adextrin-containing compound in an amount from 40 to 85% by weight ofsaid composition, and a second excipient (iii) comprising a solidfraction and optionally a liquid fraction, said second excipient (iii)being in an amount from 15 to 40% by weight of the composition and beingselected from the group consisting of polyethylene glycols andpolypropylene glycols having weight number molecular weights betweenabout 300 and 10,000 (preferably between 300 and 5,000), glycerol,propylene glycol and glycerides, comprising the steps of:

-   -   (a) homogenising a mixture comprising the drug (i) classifiable        as Class II or Class IV of the Biopharmaceutical Classification        System, e.g. a drug having low or very low water-solubility, the        first excipient (ii) and the solid fraction of the second        excipient (iii),    -   (b) feeding the mixture obtained in step (a) and optionally the        liquid fraction of the second excipient (iii) into an extruding        means having one or more mixing zones and one or more transport        zones, and    -   (c) extruding the materials fed in step (b) while operating the        extruding means at a temperature not above the melting        temperature of the solid fraction of the second excipient until        an immediate release pharmaceutical granule composition is        obtained.

More detailed ways of implementing the invention will now be describedin more details by referring both to the immediate or fast releasepharmaceutical granule composition and the process for manufacturing thesame. In a first but less preferred embodiment of the invention, thefirst excipient (ii) may be a blend of a microcrystalline cellulose anda swellable polymer and the said swellable polymer may be anuncrosslinked carboxyalkylcellulose metal salt such as for instancesodium or calcium carboxymethylcellulose.

In a preferred embodiment of the invention the first excipient (ii),whatever its nature (i.e. the aforesaid blend or a dextrin-containingcompound such as a maltodextrin), may be present in the pharmaceuticalgranule composition in an amount from about 40% to about 85% by weightof the said composition.

Microcrystalline cellulose, in particular a pharmaceutical gradethereof, is well known in the art of pharmaceutical industry for itshigh surface porosity and its outstanding capillary character. It isavailable from a variety of commercial sources, e.g. Avicel® PH 101(commercially available from FMC Corporation, Philadelphia, Pa.),Emcocel (Mendell), Vivocel (JRS) and the like. Microcrystallinecellulose is a partially purified depolymerized form of cellulose and isobtained by treating pulps derived from fibrous plant material withmineral acid. The acid preferentially attacks the less ordered oramorphous regions of the cellulose polymer chain, thereby exposing andfreeing the crystalline sites which form cellulose crystalliteaggregates. The reaction mixture is washed to remove the degradedbyproducts, the resulting wet-cake is freed of water and the driedcellulose crystallite aggregates, or more commonly microcrystallinecellulose, recovered. Microcrystalline cellulose is a white, odourless,tasteless, relatively free-flowing powder, insoluble in water, organicsolvents, dilute alkalies and dilute acids.

A swellable polymer suitable for use in the blend being an embodiment ofthe first excipient (ii) of the present invention may be defined hereinpreferably as an ionic hydrocolloid polymer which is easily misciblewith microcrystalline cellulose and which, on its own, is able to form acolloidal suspension in an aqueous environment, the colloidal particlese.g. forming a three-dimensional network or grid-like structurethroughout the liquid phase. Suitable examples of such polymer includepharmaceutical grades of sodium carboxymethylcellulose such ascommercially available under the tradenames Nymcel®, Tilose® andBlanose® (Aqualon). Preferably, the swellable polymer is a low molecularweight and/or low viscosity polymer. For instance when the swellablepolymer is an uncrosslinked carboxyalkylcellulose metal salt, it shouldpreferably have sufficient unsubstituted hydroxyl groups in order tohydrogen bond to the microcrystals of the microcrystalline celluloseupon drying and the substituent groups should have ability to impartwater-solubility. The degree of substitution of thecarboxyalkyl-cellulose should preferably not exceed about 0.9 and morepreferably be within a range of 0.5 to 0.9. Also, the viscosity of a 2%aqueous solution of the swellable polymer at 20° C. should preferably bebelow 1,000 mPa·s, more preferably within a range from about 20 to 800mPa·s.

The swellable polymer and the microcrystalline cellulose being part ofthe first excipient (ii) may be afforded separately at the time ofmaking the pharmaceutical granule compositions of the present inventionor they may be present in the form of a co-processed blend.

A co-processed blend of the swellable polymer together withmicrocrystalline cellulose is readily available, e.g. as Avicel® RC 581and Avicel CL 611 (both commercially available from FMC Corporation),both well known in the art in the form of pharmaceutically acceptablegrades. This cellulosic blend may alternatively be prepared by bringingthe two blend components into intimate contact under suitableconditions, for instance by subjecting the washed filter cake containingmicrocrystalline solids from the acid degradation of cellulose tointense attritive forces, thus resulting in a further break up of thecellulose crystallite aggregates and an increase in sub-micronparticles. As the attrition proceeds, a sufficient amount of theswellable polymer (e.g. sodium carboxymethyl cellulose) is added to theaqueous mixture in order to at least partially coat the individualmicrocrystals of the microcrystalline cellulose. Upon completion of theattrition, the blend is dried and recovered. The dried product isreadily redispersible in aqueous media to give gels. Important for itseffectiveness in the present invention is the fact that this blend is anon-disintegrating water-insoluble water-dispersible powder before it isgranulated in admixture with the poorly soluble drug and the secondexcipient. Preferably at least about 1% by weight and more preferably atleast about 30% by weight of the powder blend particles have an averagesize not greater than about 1.0 μm as determined by electron microscopicexamination.

For optimal efficiency, the weight ratio of the said swellable polymerto the microcrystalline cellulose in this first but less preferredembodiment of the first excipient (ii) for the immediate or fast releasepharmaceutical granule composition of the invention, or respectively inthe (co-processed) blend as above defined, should be above about 2:100and up to about 30:100, preferably between about 7:100 and 20:100.

In a much preferred second embodiment of the invention, the firstexcipient (ii) is a dextrin-containing compound such as describedhereinafter.

Drug dissolution enhancing agents, in particular beingdextrin-containing compounds such as maltodextrins, cyclodextrins andrelated substances such as chemically-modified derivatives thereof, inparticular their pharmaceutically acceptable grades, are well known inthe art and are available from a variety of commercial sources. They maybe collectively referred as starch cyclic linear degradation productscontaining 6 to 8 glucose residues, or alternatively as cyclicoligosaccharides composed of L-glucose molecules linked by α or β osidicbonds having a toric form. Among the above group of compounds, specialattention will be paid to cyclodextrins, and still more preferably, tomaltodextrins for inclusion in the first excipient (ii) of thepharmaceutical granule composition. Cyclodextrins are crystalline(usually white powder), non-hygroscopic, cyclic oligosaccharides derivedfrom starch. Among the most commonly useful are α-, β-, andγ-cyclodextrins which have respectively 6, 7, and 8 glucose units.Suitable representative embodiments of cyclodextrin derivative enhancingagents include 2-hydroxypropyl-β-cyclodextrin, dimethyl-β-cyclodextrin,2-hydroxyethyl-β-cyclodextrin, 3-hydroxypropyl-β-cyclodextrin, andtrimethyl-β-cyclodextrin. Maltodextrins occur as non-sweet, odourless,white powders or granules and are saccharide mixtures of polymers thatconsist of D-glucose units with a dextrose equivalent less than 20.

Preferably the amount of the first excipient (ii), particularly in theform of a dextrin-containing compound, represents from about 40% byweight to about 85% by weight, more preferably from 50% to 75% by weightof the immediate or fast release pharmaceutical granule composition ofthe invention, depending on the amounts of the other excipients (such asfillers) that may optionally be present therein.

According to the invention, the aforesaid immediate release is a releaseof at least about 50% of the said drug within 30 minutes in water,preferably a release of at least about 70% of the said drug within 10minutes in water, and more preferably a release of at least about 80% ofthe said drug within 10 minutes in water, preferably under physiologicaltemperature and pH conditions. As shown in the following examples, thepresent invention is also successfully applicable to drugs having low,but not very low, water-solubility but which are relatively highly doseddrugs (i.e. constitute from about 10% to about 20% by weight of thecomposition) for therapeutic efficiency, such as florfenicol.

The immediate or fast release pharmaceutical granule compositions ofthis invention may further comprise one or more pharmaceuticallyacceptable fillers. The aforesaid pharmaceutically acceptable fillersmay be selected for instance from hydrocolloids (such as xanthan gum),binding agents, glidants, lubricants, surfactants and diluents. The term“pharmaceutically acceptable filler” as used herein is intended to referto any material which is inert in the sense that it does not have anytherapeutic and/or prophylactic effect per se but does not adverselyinterfere with the therapeutic or prophylactic property of the drug orpharmaceutical active ingredient being formulated. The nature and amountof such fillers are, not critical to the present invention. They includefor instance binding agents such as starch, gelatin, glucose, alginicacid, sodium and calcium alginates, water-soluble acrylic (co)polymers,polyvinylpyrrolidone, polyamino-acids, ethylene-vinyl acetate copolymersand the like; natural and synthetic mineral fillers or glidants such asfumed (colloidal) silica (e.g. commercially available under thetradename Aerosil®), magnesium silicates such as talc, diatomaceousearth, aluminium silicate such as kaolinite, montmorillonite or mica,magnesium aluminium silicate such as attapulgite and vermiculite, carbonsuch as charcoal, sulphur and highly dispersed silicic acid polymers;water-soluble diluents such as lactose, sorbitol and the like. Althoughthe nature of fillers is not critical, it is however preferred when thefirst excipient (ii) is a dextrin-containing compound, that theimmediate or fast release pharmaceutical granule composition of theinvention be substantially free of micro-crystalline cellulose.

According to this invention, the drug (i) is classifiable as Class II orClass IV of the BCS and preferably has a water-solubility below about2.5 mg/ml, even between 0.1 and 1 mg/ml (i.e. “very slightly soluble” asdefined according to the United States Pharmacopeia), even below 0.1mg/ml (i.e. “practically insoluble” as defined according to the UnitedStates Pharmacopeia), even below about 5 μg/ml and may even have awater-solubility as low as about 0.2 μg/ml, at room temperature andphysiological pH. Non-limiting examples of such drugs include forinstance chlorothiazide, hydrochlorothiazide, nimodipine, flufenamicacid, furosemide, mefenamic acid, bendroflumethiazide, benzthiazide,ethacrinic acid, nitrendipine, itraconazole, saperconazole,troglitazone, prazosin, atovaquone, danazol, glibenclamide,griseofulvin, ketoconazole, carbamazepine, sulfadiazine, florfenicol,acetohexamide, ajamaline, benzbromarone, benzyl benzoate,beta-methasone, chloramphenicol, chlorpropamide, chlorthalidone,clofibrate, diazepam, dicumarol, digitoxin, ethotoin, glutethimide,hydrocortisone, hydro-flumethiazide, hydroquinine, indomethacin,ibuprofen, ketoprofen, naproxen, khellin, nitrazepam, nitrofurantoin,novalgin, oxazepam, papaverine, phenylbutazone, phenyloin, prednisolone,prednisone, reserpine, spironolactone, sulfabenzamide, sulfadimethoxine,sulfamerazine, sulfamethazine, sulfamethoxy-pyridazine,succinylsulfathiazole, sulfamethizole, sulfamethoxazole (also inadmixture with trimethoprim), sulfaphenazole, sulfathiazole,sulfisoxazole, sulpiride, testosterone and diaminopyrimidines. Suitableexamples of diamino-pyrimidines include, without limitation,2,4-diamino-5-(3,4,5-trimethoxy-benzyl)pyrimidine (known astrimethoprim), 2,4-diamino-5-(3,4-dimethoxybenzyl)pyrimidine (known asdiaveridine), 2,4 diamino-5-(3,4,6-trimethoxybenzyl)pyrmidine,2,4-diamino-5-(2-methyl-4,5-dimethoxybenzyl)pyrimidine (known asormetoprim), 2,4-diamino-5-(3,4-dimethoxy-5-bromobenzyl)pyrimidine, and2,4-diamino-5-(4-chloro-phenyl)-6-ethylpyrimidine (known aspyrimethamine). The above-mentioned drugs are known as belonging toClass II (poorly soluble, highly permeable) or Class IV (poorly soluble,poorly permeable) of the Biopharmaceutical Classification Systemaccording to G. Amidon et al. in Pharm. Res. (1995) 12:413-420. As willbe appreciated by those skilled in the art, these drugs belong tovarious therapeutic classes, including diuretics, anti-hypertensiveagents, anti-viral agents (particularly anti-HIV), antibacterial agents,antifungals, etc, and are not limited to human or veterinary use alone.

According to this invention, the granules of the immediate or fastrelease pharmaceutical granule composition preferably have a diameterranging from about 100 and 2,500 μm.

The second excipient (iii) of the immediate or fast releasepharmaceutical granule composition of this invention is preferably onewhich will not give rise to difficulties during extrusion and maysuitably be selected from the group consisting of polyethyleneglycolsand polypropyleneglycols having weight number molecular weights betweenabout 300 and about 10,000, preferably between 300 and 5,000; glycerol;propylene glycol and glycerides (such as mono-, di- and triglycerides ofpolyethyleneglycol fatty acid esters, including those commerciallyavailable under the tradename Gelucire®). Suitable examples of thelatter include those having both a portion derived from a glyceride anda portion derived from a polyethylene glycol ester. For instance, it issuitable to use polyglycosylated glycerides. The term “polyglycosylatedglycerides” as used herein denotes a mixture of mono-, di- andtriglycerides with polyethylene glycol (PEG) mono- and diesters ofC₈-C₁₈ fatty acids with a molecular weight preferably between about 200and about 600, optionally further including glycerol and/or free PEG,the hydrophilic-lipophilic balance (HLB) value of which is controlled bythe chain length of the PEG and the melting point of which is controlledby the chain length of the fatty acids, of the PEG and of the degrees ofsaturation of the fatty chains, and thus of the starting oil. Similarlythe expression “C₈-C₁₈ fatty acids” as used herein denotes mixtures invarious proportions of caprylic acid, capric acid, lauric acid, myristicacid, palmitic acid and stearic acid, when these acids are saturated,and the corresponding unsaturated acids. As is well known to the skilledperson, the proportions of these fatty acids may vary as a function ofthe starting oils. Examples of the latter include, but are not limitedto, saturated polyglycolized C₈-C₁₀ glycerides, such as the PEG-8caprylate/caprate glyceride esters sold by Gattefosse Corporation underthe tradename Labrasol; PEG-6 caprylic/capric glycerides sold by HulsAktiengesellschaft under the trade name Softigen 767; PEG-60 cornglycerides sold by Croda under the trade name Crovol M-70; Ceteareth-20sold by Henkel Corporation under the trade name Emulgin B2;diethyleneglycol monoethylethers sold by Gattefosse Corporation underthe trade name Transcutol; a mixture of C₈-C₁₈ saturatedpolyglycosylated glycerides having a melting point within a range ofabout 42-48° C. and a HLB within a range of about 8 to 16 such as soldby Gattefosse Corporation under the trade names Gelucire 48/09, Gelucire44/14 and Gelucire 42/12; and mixtures thereof in various proportions.When a polyethyleneglycol is used for instance, it may comprise a highermolecular weight solid fraction and a lower molecular weight liquidfraction, the latter acting as a plasticizer.

In a preferred embodiment of the invention the second excipient (iii),particularly when the first excipient (ii) is a dextrin-containingcompound, may be present in the immediate or fast release granulecomposition of this invention in an amount from about 10% to about 40%by weight, more preferably from 15% to 40% by weight, most preferablyfrom 20% to 30% by weight, of the said composition. In yet anotherpreferred embodiment of the invention, the weight ratio between theliquid fraction and the solid fraction of the second excipient (iii) maybe from 0:1 (no liquid fraction) to about 1:1, more preferably from 0:1to about 1:2, most preferably not more than 1:3. In yet another morepreferred embodiment of the invention, for instance when a maltodextrinis used as the first excipient (ii) and a polyethyleneglycol is used asthe second excipient (iii), the weight ratio of the first excipient (ii)to the second excipient (iii) is in a range from about 1:1 to about 5:1.

According to this invention, the immediate or fast releasepharmaceutical granule composition may optionally further comprise oneor more other drugs different from the drug having poorwater-solubility, but preferably belonging to the same therapeuticclass, in particular when combined drug therapy is desired.

The continuous process for manufacturing a pharmaceutical granulecomposition of the present invention is preferably performed in anapparatus, such as a twin screw extruder, comprising a barrel having agranulation chamber provided with inlets for supplying the drug (i), thefirst excipient (ii) and the solid fraction of the second excipient(iii), and at least one continuously operated rotating transportingmeans. The said extruder is preferably operated at a temperature notabove about 60° C., more preferably not above 45° C., most preferably ata temperature not above about 35° C., i.e. there is no need to provide aheating zone on the said extruder, therefore no need to providesophisticated means for controlling and monitoring the temperature ofthe extruder. The extruder is preferably operated at a rotating speedbetween about 5 and 450 rpm, for instance between 5 and 300 rpm,depending upon whether low shear, medium shear or high shear is desired.The continuously operated rotating transporting means of the extrudercomprises one or more mixing zones and one or more transport zones. Theconfiguration and number of these zones may be widely varied, however atleast one mixing zone is most preferred, being very advantageous toinduce interaction between the various components of the composition tobe extruded. The remaining of the screw may then consist oftransportation zones. Single or twin lead discharge screws can be used.As is standard in this art, the length to diameter ratio of eachrotating transporting means may be within a range from about 15 to about60.

The present invention also provides solid shaped articles comprising acore consisting of an immediate or fast release pharmaceutical granulecomposition as defined herein-above. This solid shaped article may be inthe form of a tablet or a hard gelatine capsule. Methods for producingtablets, such as compression, or hard gelatine capsules frompharmaceutical granule compositions are well known to those skilled inthe art. In the case of a tablet, the solid shaped article may furthercomprise a coating, according to standard practice in the art.

The solid shaped articles of the present invention may furtheroptionally contain additives typically used in the formulation of sucharticles, for instance flavoring agents (such as anethole, benzaldehyde,vanillin, ethyl vanillin, ethyl acetate, methyl salicylate and thelike), lubricants (such as magnesium stearate), sweeteners (such assucrose, mannitol, aspartame, saccharin and its salts), colorants and/orbuffering agents.

The present invention further provides a sachet comprising an immediateor fast release pharmaceutical granule composition as above defined.

The present invention provides a number of advantages over the existingformulations of poorly soluble drugs and over the existing methods ofmaking the latter, such as:

-   -   the same technology is able to formulate such drugs at low, but        also at moderate and even high drug contents, as defined herein,    -   the production cost of such formulations can be decreased by        making use of a continuous, rather than batch-wise, process,        and/or by avoiding an energy-consuming drying step,    -   formulations of poorly soluble drugs can be obtained as granules        instead of pellets, and    -   formulations of poorly soluble drugs can be obtained in the        absence of a costly pharmaceutical grade material such as        microcrystalline cellulose.

In particular the present invention provides a solid formulation offlorfenicol for oral administration, optionally together with animalfeed, to warm-blooded animals such as cattle with naturally-occurringbovine respiratory disease, swine, sheep, goats and poultry. The presentinvention also provides a solid formulation of trimethoprim, optionallyin combination with sulfadiazine (usually in a trimethoprim sulfadiazineweight ratio of about 1:5), for oral administration to fish as anantibacterial agent effective against both gram-positive andgram-negative bacteria.

Thus, the present invention also provides a method of treatment of awarm-blooded animal comprising administration to said animal of aneffective amount of a pharmaceutical granule composition comprising atleast one drug (i) classifiable as Class II or Class IV of theBiopharma-ceutical Classification System in an amount of no more thanabout 50% by weight of said pharmaceutical composition, a firstexcipient (ii) being a dextrin-containing compound in an amount fromabout 40 to about 85% by weight of said composition, and a secondexcipient (iii) comprising a solid fraction and optionally a liquidfraction, said second excipient (iii) being in an amount from about 10to about 40% by weight of the composition and being selected from thegroup consisting of polyethylene glycols and polypropylene glycolshaving weight number molecular weights between about 300 and 10,000,glycerol, propylene glycol and glycerides. In particular drug (i) usedin such a method may be florfenicol or trimethoprim.

The following examples are provided solely for the purpose ofillustrating various embodiments of the invention, and without anyintention of limiting the scope thereof.

Example 1 Twin Screw Extruder for Producing a Pharmaceutical GranuleComposition

The twin screw extruder used for performing the following pharmaceuticalgranule preparations is described in FIG. 3. It consists of sevendistinct zones, wherein zones (1), (2), (4) and (6) are three transportzones, zones (3) and (5) are two mixing zones and zone (7) is adensification zone (which could alternatively be omitted, if desired).The extruder is placed within a granulation chamber provided with inletsfor supplying the drug and the various excipients.

Examples 2 and 3 Pharmaceutical Granule Formulations Including aMaltodextrin and Xanthan Gum

The following formulations were prepared using the extruding equipmentof example 1:

Low water-soluble drug: 100 g Polyethyleneglycol 400: 52.5 gPolyethyleneglycol 4000: 187.5 g Maltodextrin 01982 622.5 g Xanthan gum:37.5 g

Maltodextrin 01982 is a neutral taste, medium DE maltodextrin with gooddispersibility which complies with European and U.S. Pharmacopeia andwhich is commercially available from Cerestar (Neuilly-sur-Seine,France). The solid fraction of the formulation consisting ofhydrochlorothiazide (example 2), PEG 4000, maltodextrin and xanthan gumwas homogenised in a planetary mixer. This mixture was fed into the twinscrew extruder at a rate of 29.9 g/min. The liquid phase (PEG400) wascontinuously pumped into the twin screw extruder at a rate of 6.9 g/min.The screw speed during the extrusion was 250 rpm. The temperature of thedifferent zones of the twin screw extruder was set at 25° C., yieldingexperimental extrusion temperatures of 25° C. in zone (1), 26° C. inzone (2), 26° C. in zone (3) and 25° C. in zones (4) and (5).

In the case of florfenicol (example 3) being used as the drug instead ofhydrochlorothiazide, the same parameters were used and the experimentaltemperatures measured in zones (1) to (5) were 26° C., 28° C., 28° C.,27° C. and 25° C. respectively.

The extruded granules were collected, sieved and further analysed fordrug dissolution (data shown in FIGS. 1 and 2, formulations B and D).FIG. 1 shows that 72% release of hydrochlorothiazide (example 2) isobtained after 10 minutes, and 90% after 25 minutes. FIG. 2 shows that80% release of florfenicol (example 3) is already obtained after 10minutes, and 100% after 20 minutes.

Examples 4 and 5 Pharmaceutical Granule Formulations IncludingMicro-Crystalline Cellulose

The following formulations were prepared using the extruding equipmentof example 1:

Low water-soluble drug: 100 g Polyethyleneglycol 400: 52.5 gPolyethyleneglycol 4000: 250 g Avicel PH 101: 298.75 g Avicel CL611:298.75 g

The solid fraction of the formulation consisting of hydrochlorothiazide(example 4), PEG 4000, Avicel PH 101/Avicel CL 611 (commerciallyavailable from FMC Corporation, Philadelphia, Pa.) was homogenised in aplanetary mixer. The homogeneous mixture was then fed into the twinscrew extruder at a rate of 27.6 g/min. The liquid phase (PEG 400) wascontinuously pumped into the twin screw extruder at a rate of 9.2g/minute. The screw speed during the extrusion was 250 rpm. Thetemperature of the different zones of the twin screw extruder was set at25° C. yielding experimental temperatures of 25° C., 28° C., 27° C., 26°C. and 25° C. in zones 1 to 5, respectively.

In the case of florfenicol (example 5) being used as a drug instead ofhydrochlorothiazide, the same parameters were used and the experimentaltemperatures measured were 25° C., 26° C., 27° C., 27° C. and 28° C. forthe zones (1) to (5) respectively.

The extruded granules were collected, sieved and further analysed fordrug dissolution (data shown in FIGS. 1 and 2, formulations A and C).FIG. 1 shows that 100% release of hydrochlorothiazide (example 4) isobtained after 10 minutes. FIG. 2 shows that 78% release of florfenicol(example 5) is already obtained after 10 minutes, and 100% after 15minutes.

Example 6 (Comparative) Pharmaceutical Pellet Formulation

A pharmaceutical pellet formulation was made according to theextrusion-spheronisation process as disclosed in the examples of U.S.Pat. No. 6,368,634, but starting from the following composition (byweight):

Florfenicol: 20% Polyethyleneglycol 400: 21% Avicel PH 101: 59%

The release rate of florfenicol from these pellets was determined as inthe previous examples and, as shown in FIG. 4, was found to be quiteslow: only 11% and 43% of the drug were dissolved after 10 minutes andafter 60 minutes, respectively.

Example 7 Pharmacokinetics of Florfenicol Granule Formulations inBroiler Chickens

The effect of a bolus oral administration of a florfenicol granuleformulation according to the invention in fasted and non-fasted broilerchickens (average weight 2-3 kgs) was compared to the effect of a bolusintravenous administration of an injectable florfenicol formulation inthe same animals. In both cases, the dosage used was 30 mg/kg.

The comparative formulation used for intravenous administration wasNuflor®, a commercially available injectable preparation with a drugconcentration of 300 mg/ml.

The granule formulation used for oral administration was preparedaccording to the procedure of examples 2 and 3, except that theflorfenicol content was 20% by weight of the formulation and themaltodextrin content was reduced accordingly.

Blood samples were taken from broilers at the following times afteradministration: 0.25 h, 0.5 h, 0.75 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 6 h, 8h and 12 hours, respectively. Plasma analysis was performed by highperformance liquid chromatography (HPLC) with UV detection withchloramphenicol as internal standard.

Results of mean plasma florfenicol concentrations (expressed in μg/ml)in chickens as a function of time are shown in FIG. 5.

Example 8 Pharmacokinetics of Florfenicol Granule Formulations in Pigs

The effect of a bolus oral administration of a florfenicol granuleformulation according to the invention in fasted and non-fasted pigs(average weight 20-35 kgs) was compared to the effect of a bolusintravenous administration of an injectable florfenicol formulation inthe same animals. In both cases, the dosage used was 15 mg/kg.

The comparative formulation used for intravenous administration wasNuflor®, a commercially available injectable preparation with a drugconcentration of 300 mg/ml.

The granule formulation used for oral administration was preparedaccording to the procedure of examples 2 and 3, except that theflorfenicol content was 20% by weight of the formulation and themaltodextrin content was reduced accordingly.

Blood samples were taken from pigs at the following times afteradministration: 0.33 h, 0.66 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 6 h, 8 h, 12h, 24 h and 30 hours, respectively. Plasma analysis was performed byhigh performance liquid chromatography (HPLC) with UV detection withchloramphenicol as internal standard.

Results of mean plasma florfenicol concentrations (expressed in μg/ml)in pigs as a function of time are shown in FIG. 6.

Example 9 Plasma Florfenicol Concentrations in Chickens after ContinuousAdministration of Granules, as Compared to Pellets, Together withDrinking Water

The effect of a continuous oral administration, together with drinkingwater, of florfenicol solid formulations in broiler chickens (averageweight 1.2-1.6 kg) was investigated. Comparison was made between thegranule florfenicol formulation of example 7 (this invention) and thepellet florfenicol formulation of example 6 (i.e. according to U.S. Pat.No. 6,368,634), both having a florfenicol content of 20% by weight, inthe same animals. In both cases, the dosage used was 30 mg florfenicolper kg of the animal, or 140 mg/L in drinking water, and administrationwas continued for 2 days.

Blood samples were taken from broilers at regular intervals, 4 timesdaily, after administration of said formulations. Plasma analysis wasperformed by high performance liquid chromatography (HPLC) with UVdetection with chloramphenicol as internal standard.

Results of mean plasma florfenicol concentrations (expressed in μg/ml)in broiler chickens as a function of time are presented in the followingtable and shown in FIG. 7 (wherein WO 94/23700 corresponds to U.S. Pat.No. 6,368,634, and PCT/BE03/00040 refers to this invention). It is quitesurprising that the mean plasma concentration of florfenicol in chickenswas continuously more than 2.3 times higher with the granule formulationof this invention than with the pellet formulation of the prior art,over the whole 48 hours period of the study. It is more particularlysurprising that the mean plasma concentration of florfenicol in chickensremained more than 9 times higher with the granule formulation of thisinvention than with the pellet formulation of the prior art over the 12hours period following the first day administration, and remained morethan 4.4 times higher with the granule formulation of this inventionthan with the pellet formulation of the prior art over the 12 hoursperiod following the second day administration. These facts areindicative of a significantly much more efficient treatment, at the samedosage, with this invention than according to the prior art formulation.

TABLE Pellets (USP Granules Time (hours) 6,368,634) (PCT/BE03/00040) 40.11 1.18 8 0.09 1.41 12 0.15 1.38 24 0.38 1.36 28 0.19 1.23 32 0.220.98 36 0.28 1.23 48 0.52 1.23 50 0.17 1.46

1. A pharmaceutical or veterinary granule composition in the form of amixture consisting essentially of: (i) florfenicol constituting from0.5% to 20% by weight of the composition, and excipients, saidpharmaceutical or veterinary granule composition providing a florfenicolrelease of at least 80% within 10 minutes in water, (ii) a firstexcipient being a maltodextrin representing from 40% by weight to 80% byweight of said composition, (iii) a wetting amount of a second excipientbeing a polyethylene glycol having a weight number molecular weightbetween 300 and 5,000, said second excipient comprising a solid fractionand a liquid fraction, and representing from 15% to 40% by weight ofsaid composition, and optionally one or more pharmaceutically acceptablefillers selected from the group consisting of hydrocolloids, glidants,lubricants, surfactants and diluents, wherein the weight ratio of saidfirst excipient (ii) to said second excipient (iii) is in a range from1:1 to 5:1.
 2. (canceled)
 3. (canceled)
 4. (canceled)
 5. Apharmaceutical or veterinary granule composition according to claim 1,wherein said granules have a diameter ranging from 100 and 2,500 μm. 6.(canceled)
 7. (canceled)
 8. (canceled)
 9. A composition comprising apharmaceutical or veterinary granule composition according to claim 1,and animal feed.
 10. A continuous process for manufacturing apharmaceutical or veterinary granule composition in the form of amixture consisting essentially of: (i) from 0.5% to 20% by weight offlorfenicol, (ii) a first excipient being a maltodextrin representingfrom 40% by weight to 80% by weight of said composition, and (iii) awetting amount of a second excipient being a polyethylene glycol havinga weight number molecular weight between 300 and 5,000, said secondexcipient comprising a solid fraction and a liquid fraction, andrepresenting from 15% to 40% by weight of said composition, wherein theweight ratio of said first excipient (ii) to said second excipient (iii)is in a range from 1:1 to 5:1, said continuous process comprising thesteps of: (a) homogenising a mixture comprising said florfenicol (i),said first excipient (ii) and the solid fraction of said secondexcipient (iii), (b) feeding the mixture obtained in step (a) and theliquid fraction of said second excipient (iii) into an extruding meanshaving one or more mixing zones and one or more transport zones, and (c)extruding the materials fed in step (b) while operating said extrudingmeans at a temperature not above the melting temperature of the solidfraction of the second excipient (iii).
 11. A process according to claim10, wherein said extruding means is a twin screw extruder.
 12. A processaccording to claim 10, wherein said extruding means is operated at atemperature not above 45° C.
 13. (canceled)
 14. A pharmaceutical orveterinary granule composition according to claim 1, providing aflorfenicol release of 100% within 20 minutes in water.
 15. Apharmaceutical or veterinary granule composition in the form of amixture comprising: (i) from 0.5% to 20% by weight florfenicol, saidpharmaceutical or veterinary granule composition providing a florfenicolrelease of at least 80% within 10 minutes in water, (ii) a firstexcipient being a maltodextrin representing from 40% by weight to 80% byweight of said composition, (iii) a wetting amount of a second excipientbeing a polyethylene glycol having a weight number molecular weightbetween 300 and 5,000, said second excipient comprising a solid fractionand a liquid fraction, and representing from 15% to 40% by weight ofsaid composition, wherein the weight ratio of said first excipient (ii)to said second excipient (iii) is within a range from 1:1 to 5:1.
 16. Anaqueous solution of a granule composition according to claim
 1. 17. Anaqueous solution of a granule composition according to claim 15.